More and more Southern California renters are sharing space to lower their housing costs. The result has created some of the most crowded rental units in the nation, led by the Inland Empire. (iStockphoto)

But even with crowded rentals, housing’s bite of the typical renting household income is still steep. For example, census data show 56.6 percent of San Bernardino County’s renters pay 30 percent or more of their income to a landlord. That’s the nation’s 16th highest financial burden tied to rent.

Riverside County rentals typically had 3.32 people, No. 2 nationally for crowded living in its 242,213 units. Its median rent was $1,313 monthly, No. 41 nationally. Despite the cost-sharing, 60.6 percent of Riverside County renters still pay 30 percent or more of their income to housing costs, fourth-worst in the U.S.

A typical Orange County rental had 3.09 people, No. 12 nationally, among 441,895 units. Median rents were fifth-costliest in the U.S. — $1,786 monthly– leaving 57.7 percent of renters paying 30 percent-plus of their income to landlords, 10th worst nationally.

And in Los Angeles County, there were 2.86 people per rental in its 1.8 million unit, ranking 21st. L.A. rents of $1,402 a month — No. 29 nationally — translated to 57.8 percent of renters paying 30 percent-plus for housing, the eighth-worst burden among the big counties studied.

Southern California is not alone with rent-payment challenges. Yes, in these 141 large U.S. counties studied the median rental unit had just 2.46 people and cost only $1,143 monthly. Still, rent is a financial burden everywhere: half of renters in these major U.S. housing markets — yes, 49.9 percent — pay 30 percent-plus to the landlord.

The debate surrounding high California rents often spins around the landlords’ inability to create enough supply. Let’s not forget that demand is part of the equation — and renters are playing the economics game, too, to lower their costs.

On the Nov. 6 ballot, Californians can vote for Proposition 10, which expands a city’s ability to control what landlords charge. There is no mandate that any municipality use such regulatory powers. This is not a simple landlord-tenant argument.

High rents create headaches for all residents. “Roomies” can mean unplanned population surges in neighborhoods. This can create a host of societal costs from jammed roads to crowded schools to strained utilities to stretched public safety resources. Sadly, even well-planned growth for rental units meets various kinds of community opposition.

The local market has adapted modestly to the challenge. Southern California is a hotbed for larger apartments that better house families who don’t want to, or can’t, own their homes. And there’s a good-sized supply of rental homes, as well.

Adding to the tenant pinch in Southern California is limited supply in one of the nation’s tightest rental markets.

Just 3.7 percent of rentals units in Los Angeles and Orange counties were vacant in the third quarter, according to census data. Only six of the 75 most-populous metro areas had lower shares of empty units. In Riverside and San Bernardino counties, 4.7 percent of rentals were vacant last quarter, 19th lowest nationally.

Local renters who need to meet a monthly household budget can’t wait for the political process or developers to play catch-up. Let my spreadsheet show you how “roomies” of all stripes makes Southern California more “affordable” for renters.

I used logic commonly applied by prospective roommates shopping for an apartment — “How much a month per person?” So I compared the census data’s regional rents to the typical number of people living in each unit to create a metric reflecting rent per resident.

For example, among the 141 large metro areas tracked, the national median rent was $1,143 monthly while the typical unit was home to 2.46 people. That’s $465 rent-per-resident.

Locally, let’s start with San Bernardino County, with the nation’s most-crowded rentals. It has the nation’s 54th priciest rents that are 7 percent higher than common major metropolitan area costs. My spreadsheet translates these patterns to rent-per-resident of $367 a month in San Bernardino County.

Surprisingly — adjusted for density — San Bernardino County per-person rents paid are 21 percent below the U.S. medial for heavily populated counties.

A similar tale is found in Riverside County, where the second-most crowded rentals can be tied to rents that are 15 percent above what’s charged in other big counties — the nation’s 41st priciest rental market. That mix equals a rent-per-resident of $395 for Riverside County, 15 percent below U.S. norms.

Can you see one reason why the Inland Empire has become the region’s population magnet? And density lowers housing costs near the coast, too.

Orange County’s got the nation’s fifth-highest median rents and the 12th most crowded rentals. Look at what roommies do to the costs: While Orange County landlords charge 56 percent more than U.S. norms, on a rent-per-resident basis ($578 a month) the cost is only 24 percent above typical costs.

Or look to Los Angeles County where rents rank No. 41 in the nation’s 21st-most crowded rentals. Denser-than-average living means while the landlord gets 23 percent above the norm, rent-per-person ($490 a month) is just 6 percent above what renters in other major metros pay.

So how can people afford Southern California’s high housing costs? They get a roommate. Or two.

Jonathan Lansner has been the Orange County Register's business columnist since 1997 and has been part of the newspaper's coverage of the local business scene since 1986. He is a native New Yorker who is a past national president of the Society of American Business Editors and Writers and a graduate of the University of Pennsylvania's Wharton School. Jon lives in Trabuco Canyon -- yes, a homeowner -- and when he's not fiddling with his trusty spreadsheet at work you can likely find him rooting for his beloved Anaheim Ducks or umpiring local lacrosse games.